Light-sensitive bipack film for four-color photography



1950 J. A. BALL ET AL 92,953

LIGHTSENSITIVE BI-PACK FILM FOR FOUR-COLOR PHOTOGRAPHY Filed Dec. 24, 1947 TRANSPARENT FILM BASE REAR FILM /SILVER HALIDE SENSITIVE 605 670 NDEVEl-OPER INSOLUBLE WATER INSOUJBLE COLLOID RED DYE SILVER HALIDE SENSITIVE 545-575 my ANTI-ABRASION LAYER SILVER HALIDE SENSITIVE 490-535 my I DEVELOPER INSOLUBLE, WATER SOLUBLE COLLOID FRO NT FILM BLUE AND VIOLET SENSITIVE SILVER HALIDE YELLOW DYE TRANSPARENT FILM BASE INVENTORS. JOSEPH ARTHUR BALL, ANDREW BRADSHAW JENNINGS and OYT/S WILLARD MURRAY 7.07%) 73M ATTORNEY Patented Jan. 3, 1950 LIGHT-SENSITIV E BIPACKFILM' FOR FOUR-COLOR PHOTOGRAPHY Joseph Arthur Ball, Los Angeles, Calif.,- Andrew Bradshaw Jennings, New Brunswick, N. Jr, and Otis Willard Murray, Burbank, Galifi, assignors to E'. I. du Pont de Nemours & Company, Wilmin'gton, De'L, a corporation of Delaware Application December 24, 1947, serialNo. 793,723-

3' Claims.

This invention relates to photography and, more particularly, to photographic films and processes for obtaining four color separation negatives.

An object of this invention is to provide improvements in the art of multicolor photography. Another object. is to. provide films suitable for the production of four color separation records.

A further obj ect-is to provide such films which can be readily exposed and processed to form separate records. Another object is to provide practical methods of processing such films. Still other objects will be apparent from the foldowing description of the invention.

The above. and other objects are obtained by the preparation and processing of the novel photographic elements of this invention. The elements consist of .bipack films which are sensitized to certain narrow wave lengths of light in the visible spectrum. The sensitized layers and cooperating filter are: so arranged. and sensitized that the. film records light from. four separate and distinct regions of the visible. spectrum. At least one of the records is strippable: from each support and can be transferred to another support in orderto be utilized in. a reproduction process.

The front film of the bipack films which: are shown in the drawing forming a partof. the pres.- ent specification consists of a tinted,. transparent film base I which has superposed in order on onev surface thereof. a hydrophilic colloid. silver halide emulsion. layer 2 which is sensitive to blue and violet light only and may contain: a removable yellow filter dye or pigment, next a stripping layer 3 which may contain a removable yellow filter dye or pigment, then: a hydrophiliccolloid silver halide emulsion layer 4 which has an extra range of strong sensitivity in the 490' to 535=mil1i-' micron region of the spectrum and finally an anti-abrasion layer 5 containing a yellow-orange dye which is capable of absorbing or screening all light below 540 millimicrons. whilez assing' lower wave lengths.

The rear film consists of a tinted, transparent film base or support 6 which has superposed in order on one surface thereof a hydrophilic colloid; silver halide emulsion layer 1 which is sensitive to red light and has its maximum sensitivity in; the 605 to 670 millimicron region of the spectrum, next isastripping layer 8 which contains a red light filter dye for the final light-sensitive layer 9 which is ahydrophilic-colloid silver halide emulsion layer which is sensitive to greenlight 2 and exhibits its maximum sensitivity in the range 545 to 5'75 milllmlcrons.

It is to be understood that the support or base of the front film is placed in the camera nearest the entrant lens and the support or base of the rear film is most: distant from the lens and. the antiabrasion layer of the front film and the outer silver halide emulsion layer of the rear film. are in contact during exposure conditions.-

It is tobe understood that each of the silver halide emulsion layers are inherently sensitive: to blue light',.in addition to having the extra sen-sis tivity specified above. However, the light filter layers prevent the lower layers from being exposed in the blue region of the spectrum.

The novel photographic elements of this lnven-- tion. are especially useful in the processes of four-color photography disclosed in Ball appli-- cation Serial No, 771,790,- filed September 2,; 1947. The photographic elements can be used to form. four individual color separation records from which four color separation positive silver image records canbe. printed as provided in said' application. The latter image records can then be converted into colored images having the absorption peaks and characteristics taught in: said application. The colored images may then be super osed: in register to reproduce a multicolor picture.

The stripping layers of the elements may" be composed of various materials which are softened or dissolved by water. Thus, they may be composed of any water-soluble colloid (viz. which has a marked solubility in water at 20 C.)" of natural" or synthetic type. Suitable colloids include water-soluble cellulose derivatives, e; g., low substituted cellulose ethers', such as methyl cellulose, ethyl cellulose, and benzyl cellulose, cellulose esters having solubilizing acid salt groups, e-. g., sodium, potassium, and ammonium" salts of cellulose acid phthal ate, cellulose ether acids, e. g., sodium cellulose glycollate', casein gelatin mixtures, water-soluble synthetic resins, e. g.,- polyvinyl alcohol and esters.

In. the preferred aspect of the invention, the stripping layersare composed of a water-soluble but photographicalkaline developer insoluble colloid. Preferred. colloids of this typeare com-- posed of water-soluble macromolecular acetals off vinyl alcohol polymers: with an aldehyde containing' sulfonic acid and/or carb'oxylic acid groups or their water-soluble salts, e. g... alkali metal, ammonium, or amine salts.

U Inaddition, there may be used; water-soluble:

' cellulose derivatives.- e. g., low substituted. ce1lu-' lose ethers, such as methyl cellulose, ethyl cellulose and benzyl cellulose, celluose esters havin solubllizlng acid salt groups, e. g., sodium, potassium, and ammonium salts of sodium cellulose glycollate, casein gelatin mixtures, watersoluble resins, e. g., polyvinyl alcohol, and esters, such as cellulose acetate.

The water-soluble macromolecular acetals can be made by the reaction of a vinyl alcohol polymer, including interpolymers, with an aldehyde containing a sulfonic acid or a carboxylic acid group under acetal forming conditions. For example, the acetalization may be conveniently carried out in solution or suspension in water or an organic solvent or diluent using a catalyst, such as phosphoric acid, sulfuric acid, hydrochloric acid, etc. Suitable procedures and aldehydes are described in United States Patent 2,310,943 and in German Patent No. 643,650. The free acid groups can be converted into salt groups by a simple neutralization as described above and in the United States patent. Preferred acetals are disclosed in application Serial Number 658,224 filed March 29, 1946, now Patent No. 2,462,534, issued February 22, 1949.

The colloid stripping materials, e. g., the watersoluble macromolecular acetals of vinyl alcohol polymers described above can be applied to the contiguous layer from a solution or dispersion in the same general manner that gelatin overcoatings are applied. The acetal layers so applied should be of such a thickness that they may be readily stripped from the layer on which they are coated. The exact thicknesses can be readily determined by experiment. Thicknesses of 0.0001 to 0.0005 inch, in general, are satisfactory. Materially thinner layers, e. g., 0.05 to 2.0 microns, in general, adhere quite firmly. They may be applied from aqueous or organic solvent solutions. Useful solvents are the water-soluble alcohols, e. g., methonal, ethanol, acetone, dioxane, etc. Mixtures of such solvents with water are quite useful. The coating solutions are preferably substantially neutral. Their pH can be adjusted by neutralizing the free acid groups with bases capable of yielding water-soluble salts, e. g., alkali metals, ammonia, and amines. Various filter dyes or pigments are added to the coating solutions prior to depositing the layers on the silver halide emulsion layers.

The bi-pack film elements after exposure in a camera are then developed to produce silver images in the various light-sensitive layers. The two films need not be fixed before further processing as this may be conveniently done later. The outer layers of the respective developed front and rear film elements are pressed into intimate contact with a second registered support, e. g., a transparent film base coated with a gelatin layer which has been wetted with water to promote adhesion with the outer layer of said front or rear films of the bi-pack. The water weakens the bond between the said outer layer and the stripping layer whereby the outer layer is stripped on" and transferred to the support. This leaves four separate color separation records which can be converted into colored images in any desired manner or they may be fixed, washed, and dried and used to print positive image color separation records'which can be converted into colored image records by color coupling development utilizing color formers which yield quinoneimine or azomethine dyes, followed by fixing, washing, and drying. The various four-color methods of re- 4 producing multicolor images disclosed in the aforesaid Ball application can be resorted to. The four dye or colored image positive records are then superposed in register which results in a multicolor positive picture.

The following example will serve to further illustrate the invention.

Example A cellulose acetate film base tinted gray is coated with a blue-sensitive gelatino-silver iodobromide emulsion to a coating weight of 50 milligrams of silver bromide per square decimeter. A layer of a water-soluble, developer insoluble osulfobenzaldehyde acetal of polyvinyl alcohol uniformly dyed with Tartrazine 0 (Colour Index 640) is coated from aqueous alcohol onto the emulsion layer. Next there is coated a gelatinosilver halide emulsion layer which is sensitized with 3,3'-diethy1-9-methyl oxycarbocyanine so that it has strong sensitivity at 514 to 520 millimicrons to a similar coating weight. Finally an antiabrasion layer is coated from a solution similar to that used for the second layer but containing Wool Orange A (Colour Index 151) or Pontacyl Brilliant Orange 2R in place of Tartrazine. This film constitutes the front film of the bi-pack.

The Color Index herein referred to is that of the Society of Dyers and Colourists, edited by F. M. Rowe, first edition, January 1924, published by The Society, Bradford, Yorkshire, England.

The rear film is made by coating a cellulose acetate film base with a gelatino-silver iodobromide emulsion layer having a coating weight of 50 milligrams of silver bromide per square decimeter and having a strong maximum sensitivity at 640 to 650 millimicrons, being sensitized with 3,3-diethyl-selenocarbocyanine iodide. A stripping layer similar to that for the second layer for the front film but dyed with Congo Red (Colour Index 370) instead of Tartrazine was coated on said emulsion layer. On said stripping layer is coated a gelatino-silver iodobromide emulsion layer having an extra range of sensitivity in the orange region of the spectrum and a maximum at about 5'70 millimicrons conferred by the addition of 6-diethylamino- 1,3-diethylthio-2-cyanine iodide and having a coating weight of 50 milligrams of silver bromide per square decimeter.

The two films are placed in a camera with their outer coated layers in contact with the base of the front film nearest the lens and exposed to a multi-color object film thereby forming color component latent image records in the respective light-sensitive records. The elements are then developed for seven minutes in a solution made by admixing the following components:

Hydroquinone grams 7.5 p-N-methylaminophenol sulfate do 5.0 Sodium sulfite (anhydrous) do 60.0 Sodium carbonate (anhydrous) do 50.0 Potassium bromide do 15.0 Water to liter 1.0

The developed films are then treated for three minutes in a stop bath of the composition:

Volumes Acetic acid (28%) 1.0 Water 20.0

The outer layer of the front film is then pressed into intimate contact with a second registered support comprising a transparent film base coated with a gelatin layer having a coating weight of about 75 milligrams per square decimeter which had been wetted with water to promote adhesion between the surfaces. The water weakens the bond between the outer layer and the stripping layer so that it may be stripped and transferred to said gelatin coated support. The stop bath may contain an inert salt, e. g., sodium sulfate (about 120 grams per liter) to prevent excessive softening of the stripping layer.

The outer layer of the rear film can be treated in like manner resulting in four separate elements bearing developed silver color component image records. These elements can be fixed, washed, and dried and used to print positive image records.

Similar front elements can be made by substituting for the Tartrazine other yellow filter dyes or pigments including Auramine 0 (Colour Index 655), Quinoline Yellow (Colour Index 801) Naphthol Yellow (Colour Index and yellow colloidal silver.

In place of the dye used in the stripping layer of the rear film in the above example, there may be substituted other dyes with similar light absorption characteristics. Among such commercially available dyes are National Lake Scarlet (Colour Index 79), and Pontacyl Brilliant Orange 2R (Colour Index 216).

In place of the sensitizing dyes for the outer emulsion layer of the above film, there can be substituted other dyes, e. g., 3,3'-diethyloxycarbocyanine iodide and 3,3-diethyl-5,5-dimethyloxycarbocyanine iodide.

In place of the sensitizing dyes for the lower emulsion layer of the front film, there can be used other sensitizers, e. g., Z-(p-dimethylaminostyryl) benzothiazole ethiodide and 2-(p-diethylaminostyryl) benzoselenazole ethiodide.

Various other stripping layers can be used in place of the specific acetal of the example. They may be composed of any of the materials described above for this purpose. Additional suitable coating compositions for this purpose include the following:

6 It is to be understood, however, that the lightscreening or filter dyes or pigments are to be added to said solutions before coating.

The silver halide emulsion layers are preferably composed of gelatin as the binding agent. However, various other natural or synthetic hydrophilic colloids can be used, if desired, e. g., agar agar, albumin, nylon, polyvinyl acetals, the hydrolyzed ethylene/vinyl acetate interpolymers of 2,397,866, etc.

An advantage of the invention is that it provides a simple and useful bipack for four color photography. The elements are simple in construction and can be readily and economically processed with the usual laboratory equipment.

What is claimed is:

1. A bipack film consisting of front and rear film elements, said front film comprising a film base having superposed on one side in order a hydrophilic colloid silver halide emulsion layer sensitive to blue light only, a stripping separator layer composed of a developer-insoluble, watersoluble colloid, a hydrophilic colloid silver halide emulsion layer having a band of extra sensitivity in the green region of the spectrum with a maximum at a position between 490 and 535 millimicrons, and an antiabrasion layer containing a yellow-orange filtering material which absorbs light shorter than 540 millimicrons and passes longer wave lengths, at least one of said two innermost layers containing a yellow filtering material; said rear film comprising a film base bearing in order on one side a hydrophilic colloid silver halide emulsion layer which has an extra band of sensitivity in the red region of the spectrum with a maximum at a position within the region from 605 to 670 millimicrons, a stripping separator layer composed of a developer insoluble, water-soluble colloid and containing a red light filter dye for the following hydrophilic colloid silver halide emulsion layer having a band of extra sensitivity in the yellow region of the spectrum with a maximum at a position within the region from 545 to 575 millimicrons.

2. A bipack film as set forth in claim 1 wherein said stripping layers are composed of a developer insoluble, water-soluble colloid, and said hydrophilic colloid of said emulsion layers is gelatin.

3. A bipack film as set forth in claim 1 wherein said silver halide emulsion layers contain gelatin as the hydrophilic colloid and the stripping layers are composed of a water-soluble acetal of a vinyl alcohol polymer with an aldehyde containing a group taken from the class consisting of free carboxylic acid groups, free sulfonic acid groups, and their water-soluble salts.

JOSEPH ARTHUR BALL. ANDREW BRADSHAW JENNINGS. OTIS WILLARD MURRAY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,900,468 Sease Mar. 7, 1933 2,167,732 Verkinderen Aug. 1, 1939 2,182,814 Marasco Dec. 12, 1939 2415,442 Rackett Feb, 11, 1947 

1. A BIPACK FILM CONSISTING OF FRONT AND REAR FILM ELEMENTS, SAID FRONT FILM COMPRISING A FILM BASE HAVING SUPERPOSED ON ONE SIDE IN ORDER A HYROPHILIC COLLOID SILVER HALIDE EMULSION LAYER SENSITIVE TO BLUE LIGHT ONLY, A STRIPPING SEPARATOR LAYER COMPOSED OF A DEVELOPER-INSOLUBLE, WATERSOLUBLE COLLOID, A HYDROPHILIC COLLOID SILVER HALIDE EMULSION LAYER HAVING A BAND OF EXTRA SENSITIVITY IN THE GREEN REGION OF THE SPECTRUM WITH A MAXIMUM AT A POSITION BETWEEN 490 AND 535 MILLIMICRONS, AND AN ANTIABRASION LAYER CONTAINING A YELLOW-ORANGE FILTERING MATERIAL WHICH ABSORBS LIGHT SHORTER THAN 540 MILLIMICRONS AND PASSES LONGER WAVE LENGTHS, AT LEAST ONE OF SAID TWO INNERMOST LAYERS CONTAINING A YELLOW FILTERING MATERIAL; SAID REAR FILM COMPRISING A FILM BASE BEARING IN ORDER ON ONE SIDE A HYDROPHILIC COLLOID SILVER HALIDE EMULSION LAYER WHICH HAS AN EXTRA BAND OF SENSITIVITY IN THE RED REGION OF THE SPECTRUM WITH A MAXIMUM AT A POSITION WITHIN THE REGION FROM 605 TO 670 MILLIMICRONS, A STRIPPING SEPARATOR LAYER COMPOSED OF A DEVELOPER INSOLUBLE, WATER-SOLUBLE COLLOID AND CONTAINING A RED LIGHT FILTER DYE FOR THE FOLLOWING HYDROPHILIC COLLOID SILVER HALIDE EMULSION LAYER HAVING A BAND OF EXTRA SENSITIVITY IN THE YELLOW REGION OF THE SPECTRUM WITH A MAXIMUM AT A POSITION WITHIN THE REGION FROM 545 TO 575 MILLIMICRONS. 